What is the National Aeronautics and Space Administration's (NASA) future now that Atlantis has landed and the shuttle program is over? If NASA persists in using nuclear power in space, the agency's future is threatened.

Between November 25 and December 15, 2011, NASA plans to launch for use on Mars a rover fueled with 10.6 pounds of plutonium, more plutonium than ever used on a rover.

The mission has a huge cost: $2.5 billion.

But if there is an accident before the rover is well on its way to Mars and plutonium is released on Earth, its cost stands to be yet more gargantuan.

NASA's final environmental impact statement for what it calls its Mars Science Laboratory mission says that if plutonium is released on Earth, the cost could be as high as $1.5 billion to decontaminate each square mile of "mixed-use urban areas" impacted.

What's the probability of an accident releasing plutonium? The NASA document says, "the probability of an accident with a release of plutonium" is 1 in 220 "overall."

If you knew your chance of not surviving an airplane flight - or just a drive in a car - was 1 in 220, would you take that trip?

And is this enormous risk necessary?

In two weeks, there'll be a NASA mission demonstrating a clear alternative to atomic energy in space: solar power.

On August 5, NASA plans to launch a solar-powered space probe it has named Juno to Jupiter. There's no atomic energy involved, although NASA, for decades, has insisted that nuclear power is necessary for space devices beyond the orbit of Mars. With Juno, NASA will be showing it had that wrong.

"Juno will provide answers to critical science questions about Jupiter, as well as key information that will dramatically enhance present theories about the early formation of our own solar system," says NASA on its web site. "In 2016, the spinning, solar-powered Juno spacecraft will reach Jupiter." It will be equipped with, "instruments that can sense the hidden world beneath Jupiter's colorful clouds" and make 33 passes of Jupiter.

As notes Aviation Week and Space Technology, "The unique spacecraft will set a record by running on solar power rather than nuclear radioisotope thermoelectric generators previously used to operate spacecraft that far from the Sun."

The Mars rover to be launched, named Curiosity by NASA, will be equipped with these radioisotope thermoelectric generators using plutonium, the deadliest radioactive substance.

Juno, a large craft - 66 feet wide - will be powered by solar panels built by a Boeing subsidiary, Spectrolab. The panels can convert 28 percent of the sunlight that hits them to electricity. They'll also produce heat to keep Juno's instruments warm. This mission's cost is $1.1 billion.

In fact, Juno is not a wholly unique spacecraft. In 2004, the European Space Agency launched a space probe called Rosetta that is also solar-powered. Its mission is to orbit and land on a comet - beyond the orbit of Jupiter.

Moreover, there have been major developments in "solar sails" to propel spacecraft. Last year, the Japan Aerospace Exploration Agency launched its IKAROS spacecraft with solar sails taking it to Venus. In January, NASA itself launched its NanoSail-D spacecraft. The Planetary Society has been developing several spacecraft that will take advantage of photons emitted by the sun to travel through the vacuum of space.

At no point will Juno (or the other solar spacecrafts) be a threat to life on Earth. This includes Juno posing no danger when, in 2013, it makes a flyby of Earth. Such flybys making use of Earth's gravity to increase a spacecraft's velocity have constituted dangerous maneuvers when, in recent years, they've involved plutonium-powered space probes such as NASA's Galileo and Cassini probes.

Curiosity is a return to nuclear danger.

NASA's final environmental impact statement admits that a large swath of Earth could be impacted by plutonium in an accident involving it. The document's section on "Impacts of Radiological Releases" says "the affected environment" could include "the regional area near the Cape Canaveral Air Force Station and the global area."

"Launch area accidents would initially release material into the regional area, defined ... to be within ... 62 miles of the launch pad," says the document. This is an area from Cape Canaveral west to Orlando.

But, "since some of the accidents result in the release of very fine particles less than a micron in diameter, a portion of such releases could be transported beyond ... 62 miles," it goes on. These particles could become "well-mixed in the troposphere" - the atmosphere five to nine miles high - "and have been assumed to potentially affect persons living within a latitude band from approximately 23-degrees north to 30-degrees north." That's a swath through the Caribbean, across North Africa and the Mideast, then India and China, Hawaii and other Pacific islands, and Mexico and southern Texas.

Then, as the rocket carrying Curiosity up gains altitude, the impacts of an accident in which plutonium is released would be even broader. The plutonium could affect people "anywhere between 28-degrees north and 28-degrees south latitude," says the NASA document. That's a band around the midsection of the Earth, including much of South America, Africa and Australia.

Dr. Helen Caldicott, president emeritus of Physicians for Social Responsibility, has long emphasized that a pound of plutonium, if uniformly distributed, could hypothetically give a fatal dose of lung cancer to every person on Earth. A pound, even 10.6 pounds, could never be that uniformly distributed, of course. But an accident in which plutonium is released by a space device as tiny particles falling to Earth maximizes its lethality. A millionth of a gram of plutonium can be a fatal dose. The pathway of greatest concern is the breathing in of plutonium particles.

As the NASA environmental impact statement puts it, "Particles smaller than about 5 microns would be transported to and remain in the trachea, bronchi, or deep lung regions." The plutonium particles "would continuously irradiate lung tissue."

"A small fraction would be transported over time directly to the blood or to lymph nodes and then to the blood," it continues. Once plutonium "has entered the blood via ingestion or inhalation, it would circulate and be deposited primarily in the liver and skeletal system." Also, says the document, some of the plutonium would migrate to the testes or ovaries.

The cost of decontamination of areas affected by the plutonium could be, according to the NASA statement, $267 million for each square mile of farmland, $478 million for each square mile of forests and $1.5 billion for each square mile of "mixed-use urban areas."

The NASA document lists "secondary social costs associated with the decontamination and mitigation activities" as: "Temporary or longer term relocation of residents; temporary or longer term loss of employment; destruction or quarantine of agricultural products including citrus crops; land use restrictions which could affect real estate values, tourism and recreational activities; restriction or bans on commercial fishing; and public health effects and medical care."

Furthermore, the isotope of plutonium used as fuel on space devices is especially hot. It is Plutonium-238, distinct from Plutonium-239, the isotope of plutonium used in atomic bombs. Plutonium-238 has a far shorter half-life - 87.8 years - as compared to Plutonium-239, which has a half-life of 24,500 years. An isotope's half-life is the period in which half of its radioactivity is expended.

As Dr. Arjun Makhijani, a nuclear physicist and president of the Institute for Energy and Environmental Research, has explained, Plutonium-238, "is about 270 times more radioactive than Plutonium-239 per unit of weight." Thus, in radioactivity, the 10.6 pounds of Plutonium-238 that is to be used on the Mars Science Laboratory mission would be the equivalent of 2,862 pounds of Plutonium-239. The atomic bomb dropped on Nagasaki was fueled with 15 pounds of Plutonium-239.

As to why the use of a plutonium-powered rover on Mars - considering that NASA has successfully used solar-powered rovers on Mars - the NASA environmental impact statement says that a "solar-powered rover ... would not be capable of operating over the full range of scientifically desirable landing site latitudes" on this mission.

There's more to it. For many decades, there has been a marriage of nuclear power and space at NASA. The use of nuclear power on space missions has been heavily promoted by the US Department of Energy (DOE) and its predecessor agency, the US Atomic Energy Commission (AEC) and by the many DOE (previously AEC) national laboratories, including Los Alamos and Oak Ridge. This provides work for these government entities. Also, the manufacturers of nuclear-powered space devices - General Electric was a pioneer in this - have pushed their products. Further, NASA has sought to coordinate its activities with the US military. The military for decades has planned for the deployment of nuclear-powered weapons in space.

Personifying the NASA-military connection now is NASA Administrator Charles Bolden, a former NASA astronaut and Marine Corps major general. Appointed by President Barack Obama, he is a booster of radioisotope thermoelectric generators as well as rockets using nuclear power for propulsion. The United States has spent billions of dollars through the years on such rockets, but none have ever taken off. The programs have all ended up cancelled, largely out of concern about a nuclear-powered rocket blowing up on launch or falling back to Earth.

Accidents have happened in the US space nuclear program. Of the 26 space missions that have used plutonium that are listed in the NASA environmental impact statement for the Mars Science Laboratory mission, three underwent accidents, admits the document.

The worst occurred in 1964 and involved, it notes, the SNAP-9A plutonium system aboard a satellite that failed to achieve orbit and dropped to Earth, disintegrating as it fell. The 2.1 pounds of plutonium fuel dispersed widely over the Earth, and Dr. John Gofman, professor of medical physics at the University of California at Berkeley, has long linked this accident to an increase in global lung cancer. With the SNAP-9A accident, NASA switched to solar energy on satellites. Now all satellites and the International Space Station are solar-powered.

There was a near-miss involving a nuclear disaster and a space shuttle. The ill-fated Challenger's next mission in 1986 was to loft a plutonium-powered space probe.

Safe energy activist Leah Karpen of Asheville, North Carolina says: "Every expansion of plutonium research, development and transportation of this deadly material increases the risk of nuclear accident or theft. In addition, plutonium production is expensive and diverts resources from the more important social needs of our society today, and in the future." She urges NASA "to reconsider the use of nuclear" and go with solar instead.

Jeremy Maxand, executive director of the Idaho-based Snake River Alliance, calls on NASA and the DOE to "take this opportunity to move space exploration in a sustainable direction with regard to power. Using solar rather than nuclear to power the Mars Science Laboratory Mission would keep the U.S. safe, advance energy technologies that are cleaner and more secure, be more fiscally responsible, and set a responsible example to other countries as they make decisions about their energy future."

Ace Hoffman of Carlsbad, California speaks of "today's nuclear NASA" and a "closed society of dangerous, closed-minded 'scientists' who are hoodwinking the American public and who are guilty of premeditated random murder." He adds: "The media has a duty to learn the truth rather than parrot NASA's blanketly-false assertions."

NASA, in response to the criticisms, repeatedly states in the document: "NASA and the DOE take very seriously the possibility that an action they take could potentially result in harm to humans or the environment. Therefore, both agencies maintain vigorous processes to reduce the potential for such events."

Involved in challenging the mission is the Global Network Against Weapons and Nuclear Power in Space. Bruce Gagnon, coordinator of the Maine-based organization, says that, "NASA sadly appears committed to maintaining their dangerous alliance with the nuclear industry. Both entities view space as a new market for the deadly plutonium fuel."

Says Gagnon: "The taxpayers are being asked once again to pay for nuclear missions that could endanger the life of all the people on the planet.... Have we not learned anything from Chernobyl and Fukushima? We don't need to be launching nukes into space. It's not a gamble we can afford to take."

With the return of Atlantis and the end of the shuttle program, there are concerns about this being the "end" of the US space program.

If NASA continues to insist on mixing atomic energy and space, an accident - a nuclear disaster overhead - that indeed could end the space program.

What is the National Aeronautics and Space Administration's (NASA) future now that Atlantis has landed and the shuttle program is over? If NASA persists in using nuclear power in space, the agency's future is threatened.

Between November 25 and December 15, 2011, NASA plans to launch for use on Mars a rover fueled with 10.6 pounds of plutonium, more plutonium than ever used on a rover.

The mission has a huge cost: $2.5 billion.

But if there is an accident before the rover is well on its way to Mars and plutonium is released on Earth, its cost stands to be yet more gargantuan.

NASA's final environmental impact statement for what it calls its Mars Science Laboratory mission says that if plutonium is released on Earth, the cost could be as high as $1.5 billion to decontaminate each square mile of "mixed-use urban areas" impacted.

What's the probability of an accident releasing plutonium? The NASA document says, "the probability of an accident with a release of plutonium" is 1 in 220 "overall."

If you knew your chance of not surviving an airplane flight - or just a drive in a car - was 1 in 220, would you take that trip?

And is this enormous risk necessary?

In two weeks, there'll be a NASA mission demonstrating a clear alternative to atomic energy in space: solar power.

On August 5, NASA plans to launch a solar-powered space probe it has named Juno to Jupiter. There's no atomic energy involved, although NASA, for decades, has insisted that nuclear power is necessary for space devices beyond the orbit of Mars. With Juno, NASA will be showing it had that wrong.

"Juno will provide answers to critical science questions about Jupiter, as well as key information that will dramatically enhance present theories about the early formation of our own solar system," says NASA on its web site. "In 2016, the spinning, solar-powered Juno spacecraft will reach Jupiter." It will be equipped with, "instruments that can sense the hidden world beneath Jupiter's colorful clouds" and make 33 passes of Jupiter.

As notes Aviation Week and Space Technology, "The unique spacecraft will set a record by running on solar power rather than nuclear radioisotope thermoelectric generators previously used to operate spacecraft that far from the Sun."

The Mars rover to be launched, named Curiosity by NASA, will be equipped with these radioisotope thermoelectric generators using plutonium, the deadliest radioactive substance.

Juno, a large craft - 66 feet wide - will be powered by solar panels built by a Boeing subsidiary, Spectrolab. The panels can convert 28 percent of the sunlight that hits them to electricity. They'll also produce heat to keep Juno's instruments warm. This mission's cost is $1.1 billion.

In fact, Juno is not a wholly unique spacecraft. In 2004, the European Space Agency launched a space probe called Rosetta that is also solar-powered. Its mission is to orbit and land on a comet - beyond the orbit of Jupiter.

Moreover, there have been major developments in "solar sails" to propel spacecraft. Last year, the Japan Aerospace Exploration Agency launched its IKAROS spacecraft with solar sails taking it to Venus. In January, NASA itself launched its NanoSail-D spacecraft. The Planetary Society has been developing several spacecraft that will take advantage of photons emitted by the sun to travel through the vacuum of space.

At no point will Juno (or the other solar spacecrafts) be a threat to life on Earth. This includes Juno posing no danger when, in 2013, it makes a flyby of Earth. Such flybys making use of Earth's gravity to increase a spacecraft's velocity have constituted dangerous maneuvers when, in recent years, they've involved plutonium-powered space probes such as NASA's Galileo and Cassini probes.

Curiosity is a return to nuclear danger.

NASA's final environmental impact statement admits that a large swath of Earth could be impacted by plutonium in an accident involving it. The document's section on "Impacts of Radiological Releases" says "the affected environment" could include "the regional area near the Cape Canaveral Air Force Station and the global area."

"Launch area accidents would initially release material into the regional area, defined ... to be within ... 62 miles of the launch pad," says the document. This is an area from Cape Canaveral west to Orlando.

But, "since some of the accidents result in the release of very fine particles less than a micron in diameter, a portion of such releases could be transported beyond ... 62 miles," it goes on. These particles could become "well-mixed in the troposphere" - the atmosphere five to nine miles high - "and have been assumed to potentially affect persons living within a latitude band from approximately 23-degrees north to 30-degrees north." That's a swath through the Caribbean, across North Africa and the Mideast, then India and China, Hawaii and other Pacific islands, and Mexico and southern Texas.

Then, as the rocket carrying Curiosity up gains altitude, the impacts of an accident in which plutonium is released would be even broader. The plutonium could affect people "anywhere between 28-degrees north and 28-degrees south latitude," says the NASA document. That's a band around the midsection of the Earth, including much of South America, Africa and Australia.

Dr. Helen Caldicott, president emeritus of Physicians for Social Responsibility, has long emphasized that a pound of plutonium, if uniformly distributed, could hypothetically give a fatal dose of lung cancer to every person on Earth. A pound, even 10.6 pounds, could never be that uniformly distributed, of course. But an accident in which plutonium is released by a space device as tiny particles falling to Earth maximizes its lethality. A millionth of a gram of plutonium can be a fatal dose. The pathway of greatest concern is the breathing in of plutonium particles.

As the NASA environmental impact statement puts it, "Particles smaller than about 5 microns would be transported to and remain in the trachea, bronchi, or deep lung regions." The plutonium particles "would continuously irradiate lung tissue."

"A small fraction would be transported over time directly to the blood or to lymph nodes and then to the blood," it continues. Once plutonium "has entered the blood via ingestion or inhalation, it would circulate and be deposited primarily in the liver and skeletal system." Also, says the document, some of the plutonium would migrate to the testes or ovaries.

The cost of decontamination of areas affected by the plutonium could be, according to the NASA statement, $267 million for each square mile of farmland, $478 million for each square mile of forests and $1.5 billion for each square mile of "mixed-use urban areas."

The NASA document lists "secondary social costs associated with the decontamination and mitigation activities" as: "Temporary or longer term relocation of residents; temporary or longer term loss of employment; destruction or quarantine of agricultural products including citrus crops; land use restrictions which could affect real estate values, tourism and recreational activities; restriction or bans on commercial fishing; and public health effects and medical care."

Furthermore, the isotope of plutonium used as fuel on space devices is especially hot. It is Plutonium-238, distinct from Plutonium-239, the isotope of plutonium used in atomic bombs. Plutonium-238 has a far shorter half-life - 87.8 years - as compared to Plutonium-239, which has a half-life of 24,500 years. An isotope's half-life is the period in which half of its radioactivity is expended.

As Dr. Arjun Makhijani, a nuclear physicist and president of the Institute for Energy and Environmental Research, has explained, Plutonium-238, "is about 270 times more radioactive than Plutonium-239 per unit of weight." Thus, in radioactivity, the 10.6 pounds of Plutonium-238 that is to be used on the Mars Science Laboratory mission would be the equivalent of 2,862 pounds of Plutonium-239. The atomic bomb dropped on Nagasaki was fueled with 15 pounds of Plutonium-239.

As to why the use of a plutonium-powered rover on Mars - considering that NASA has successfully used solar-powered rovers on Mars - the NASA environmental impact statement says that a "solar-powered rover ... would not be capable of operating over the full range of scientifically desirable landing site latitudes" on this mission.

There's more to it. For many decades, there has been a marriage of nuclear power and space at NASA. The use of nuclear power on space missions has been heavily promoted by the US Department of Energy (DOE) and its predecessor agency, the US Atomic Energy Commission (AEC) and by the many DOE (previously AEC) national laboratories, including Los Alamos and Oak Ridge. This provides work for these government entities. Also, the manufacturers of nuclear-powered space devices - General Electric was a pioneer in this - have pushed their products. Further, NASA has sought to coordinate its activities with the US military. The military for decades has planned for the deployment of nuclear-powered weapons in space.

Personifying the NASA-military connection now is NASA Administrator Charles Bolden, a former NASA astronaut and Marine Corps major general. Appointed by President Barack Obama, he is a booster of radioisotope thermoelectric generators as well as rockets using nuclear power for propulsion. The United States has spent billions of dollars through the years on such rockets, but none have ever taken off. The programs have all ended up cancelled, largely out of concern about a nuclear-powered rocket blowing up on launch or falling back to Earth.

Accidents have happened in the US space nuclear program. Of the 26 space missions that have used plutonium that are listed in the NASA environmental impact statement for the Mars Science Laboratory mission, three underwent accidents, admits the document.

The worst occurred in 1964 and involved, it notes, the SNAP-9A plutonium system aboard a satellite that failed to achieve orbit and dropped to Earth, disintegrating as it fell. The 2.1 pounds of plutonium fuel dispersed widely over the Earth, and Dr. John Gofman, professor of medical physics at the University of California at Berkeley, has long linked this accident to an increase in global lung cancer. With the SNAP-9A accident, NASA switched to solar energy on satellites. Now all satellites and the International Space Station are solar-powered.

There was a near-miss involving a nuclear disaster and a space shuttle. The ill-fated Challenger's next mission in 1986 was to loft a plutonium-powered space probe.

Safe energy activist Leah Karpen of Asheville, North Carolina says: "Every expansion of plutonium research, development and transportation of this deadly material increases the risk of nuclear accident or theft. In addition, plutonium production is expensive and diverts resources from the more important social needs of our society today, and in the future." She urges NASA "to reconsider the use of nuclear" and go with solar instead.

Jeremy Maxand, executive director of the Idaho-based Snake River Alliance, calls on NASA and the DOE to "take this opportunity to move space exploration in a sustainable direction with regard to power. Using solar rather than nuclear to power the Mars Science Laboratory Mission would keep the U.S. safe, advance energy technologies that are cleaner and more secure, be more fiscally responsible, and set a responsible example to other countries as they make decisions about their energy future."

Ace Hoffman of Carlsbad, California speaks of "today's nuclear NASA" and a "closed society of dangerous, closed-minded 'scientists' who are hoodwinking the American public and who are guilty of premeditated random murder." He adds: "The media has a duty to learn the truth rather than parrot NASA's blanketly-false assertions."

NASA, in response to the criticisms, repeatedly states in the document: "NASA and the DOE take very seriously the possibility that an action they take could potentially result in harm to humans or the environment. Therefore, both agencies maintain vigorous processes to reduce the potential for such events."

Involved in challenging the mission is the Global Network Against Weapons and Nuclear Power in Space. Bruce Gagnon, coordinator of the Maine-based organization, says that, "NASA sadly appears committed to maintaining their dangerous alliance with the nuclear industry. Both entities view space as a new market for the deadly plutonium fuel."

Says Gagnon: "The taxpayers are being asked once again to pay for nuclear missions that could endanger the life of all the people on the planet.... Have we not learned anything from Chernobyl and Fukushima? We don't need to be launching nukes into space. It's not a gamble we can afford to take."

With the return of Atlantis and the end of the shuttle program, there are concerns about this being the "end" of the US space program.

If NASA continues to insist on mixing atomic energy and space, an accident - a nuclear disaster overhead - that indeed could end the space program.